It was a long time ago, but wasn’t the idea that systems of a certain complexity with a very high reliability are impossible? My phone, at least, is not a paragon of reliability.
I don’t think they were that clear about reliability metrics. It was obscure but the slightly older Safeguard ABM software load was of that order of complexity magnitude and tested reliability. Thank goodness of course we never had a real test. Admittedly I have a small axe to grind, having known some of those CPSR people.